Phosphatidylserine/Prothrombin Antibodies (IgG, IgM)
Also known as: PSPT IgM Antibodies, aPS/PT IgG, IgM
Use
The assay is intended for the detection of IgG and IgM class antibodies to the phosphatidylserine/prothrombin complex in serum or plasma. A positive result suggests the possibility of autoimmune thrombotic disorders such as antiphospholipid syndrome (APS) or lupus-like thrombotic diseases. PS–PT IgG and IgM antibodies are non-criteria APS antibodies and may support APS diagnosis when other standard antibodies (eg, cardiolipin, β2‑glycoprotein I, lupus anticoagulant) are negative. They also correlate with lupus anticoagulant presence and may serve as a surrogate when anticoagulants interfere with lupus anticoagulant testing.
Special Instructions
Not provided.
Limitations
Because there is a lack of international standardization, results from different manufacturers’ assay methods may not be used interchangeably. Anticoagulants do not interfere with PS–PT antibody testing (ELISA-based), but anticoagulant therapies may cause false-positive lupus anticoagulant results. IgM results near cutoff may reflect an acute-phase response rather than APS and should be correlated clinically.
Methodology
Immunoassay (ELISA)
Biomarkers
LOINC Codes
- 85359-8 - PS-prothrom cmplx IgG SerPl IA-aCnc
Result Turnaround Time
1-3 days
Related Documents
For more information, please review the documents below
Specimen
Plasma
Volume
1 mL (0.5 mL minimum)
Minimum Volume
Not provided
Container
sodium citrate (light blue‑top) tube
Collection Instructions
Collect platelet‑poor plasma: centrifuge light blue‑top tube 15 minutes at approx. 1500 × g within 60 minutes of collection; remove plasma avoiding buffy layer; centrifuge again; plasma must contain <10,000/mcL platelets.
Causes for Rejection
Gross hemolysis; grossly lipemic
Stability Requirements
| Temperature | Period |
|---|---|
| Room Temperature | 7 days |
| Refrigerated | 30 days |
| Frozen | 30 days |
Other tests from different labs that may be relevant